import math
x1, y1, x2, y2 = map(float,input().split())
a = abs(x1-x2)
b = abs(y1-y2)

print(math.sqrt(a*a+b*b)) import math math x1, y1, x2, y2 = map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 a = abs(x1-x2) a abs(x1-x2) abs x1-x2 x1 x2 b = abs(y1-y2) b abs(y1-y2) abs y1-y2 y1 y2 print(math.sqrt(a*a+b*b)) print math.sqrt(a*a+b*b) math.sqrt math sqrt a*a+b*b a*a a a b*b b b a = abs(x1-x2) abs(x1-x2) a y1, x2, y2 = map(float,input().split()) map(float,input().split()) y1 b = abs(y1-y2) abs(y1-y2) b y2 = map(float,input().split()) map(float,input().split()) y2 x2, y2 = map(float,input().split()) map(float,input().split()) x2 x1, y1, x2, y2 = map(float,input().split()) map(float,input().split()) x1
import math
x1, y1, x2, y2 = map(float,input().split())
a = abs(x1-x2)
b = abs(y1-y2)

print(math.sqrt(a*a+b*b))
